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Smart and Sustainable Food Packaging Material Keeps Harmful Microbes at Bay

This material can also prolong the shelf-life of fresh fruit by two to three days and help meet the emerging need to reduce food waste and enhance food safety and quality without compromising the environment.

While modern food packaging has found ways to allow for clean, reliable, safe, and shelf-stable methods of food storage and transport, most packaging materials are designed to be single-use and not recycled. The majority of food packaging come in the form of plastic and often end up in waterways, causing massive plastic pollution of oceans and exacerbating the already serious waste problem. Currently, the packaging industry is the largest and growing consumer of synthetic plastics derived from fossil fuels and food packaging plastics account for the bulk of plastic waste.

In Singapore alone, Singapore’s National Environment Agency has revealed that packaging is a major source of trash. Of the 1.76 million tonnes of waste disposed of by domestic sources in 2018, one-third of it was packaging waste and 55 per cent of it was plastic, urging the development of more sustainable food packaging materials.

Working on cutting edge technologies in agriculture and food and focused on developing non-toxic and environmentally safe nanomaterials, a group of scientists from Nanyang Technological University in Singapore (NTU) in Singapore and Harvard T.H. Chan School of Public Health in the US has innovated a “smart” food packaging material that is not only biodegradable and sustainable, but can also kill harmful pathogenic microbes.

“Food safety and waste have become a major societal challenge of our times with immense public health and economic impact which compromises food security. One of the most efficient ways to enhance food safety and reduce spoilage and waste is to develop efficient biodegradable non-toxic food packaging materials. In this study, we used nature-derived compounds including biopolymers, non-toxic solvents, and nature-inspired antimicrobials and develop scalable systems to synthesise smart antimicrobial materials, which can be used not only to enhance food safety and quality, but also to eliminate the harm to the environment and health and reduce the use of non-biodegradable plastics at global level and promote sustainable agri-food systems,” said Professor Philip Demokritou, Adjunct Professor of Environmental Health at Harvard Chan School, who is also Director of Nanotechnology and Nanotoxicology Center and Co-director of NTU-Harvard Initiative on Sustainable Nanotechnology.

This novel material is produced by electrospinning cellulose nanocrystals, zein – a corn protein, which is also a waste by-product in ethanol production – and starch to form multistimuli-responsive fibres. The material also incorporates a cocktail of antimicrobials such as thyme oil, citric acid, and nisin.

To test its suitability for food packaging, the researchers conducted lab experiments on the material wherein they exposed the material to high levels of humidity or enzymes from harmful bacteria. Their tests revealed that the fibres in the packaging can release the necessary amounts of antimicrobial compounds in response to said stressors, effectively killing common food-borne disease-causing bacteria such as E.coliListeria, and various fungi. This feature enables the packaging to endure several exposures and even last for months.

Additionally, since the antimicrobial compounds can fight bacteria that grow on both the packaging and the surface of the food, it is potentially applicable to meat, raw fruits, ready-to-eat foods, and vegetables. To demonstrate this, the scientists wrapped strawberries in their new packaging material and found that the fruits remained fresh for seven days before developing mould. In contrast, strawberries kept in conventional plastic box containers only stayed fresh for four days.

“This invention would serve as a better option for packaging in the food industry, as it has demonstrated superior antimicrobial qualities in combatting a myriad of food-related bacteria and fungi that could be harmful to humans. The packaging can be applied to various produces such as fish, meat, vegetables, and fruits. The smart release of antimicrobials only when bacteria or high humidity is present, provides protection only when needed thus minimising the use of chemicals and preserving the natural composition of foods packaged,” explained Professor Mary Chan, Director of NTU’s Centre of Antimicrobial Bioengineering, who co-led the project.

Within the next few years, the NTU and Harvard Chan School researchers hope to scale up their technology with an industrial partner and commercialise it. When scaled up, this biodegradable material is expected to substitute current packaging materials, thereby reducing the amount of plastic waste generated. At present, the team is also researching other technologies to develop biopolymer-based smart food package materials to enhance food safety and quality.

“The NTU-Harvard Chan School food packaging material would serve as a sustainable solution for companies like us who want to cut down on the usage of plastic and embrace greener alternatives. As ComCrop looks to ramp up product[s] to boost Singapore’s food production capabilities, the volume of packaging we need will increase in sync, and switching to a material such as this would help us have double the impact. The wrapping’s antimicrobial properties, which could potentially extend the shelf life of our vegetables, would serve us well. The packaging material holds promise to the industry, and we look forward to learning more about the wrapping and possibly adopting it for our usage someday,” commented Mr Peter Barber, CEO of ComCrop, a Singapore company that pioneered urban rooftop farming in his independent assessment of the innovation. [APBN]

Source: Aytac et al. (2021). Enzyme- and Relative Humidity-Responsive Antimicrobial Fibers for Active Food Packaging. American Chemical Society (ACS) Applied Materials & Interfaces, 13(42), 50298–50308.